Fluorophenoxyphenoxypropionates and derivatives thereof

ABSTRACT

Novel intermediates useful in the preparation of fluorophenoxyphenoxypropionates and derivatives thereof which possess herbicidal activity selectively in the presence of broadleaf crops.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of Ser. No. 528,711 filedSept. 1, 1983.

BACKGROUND OF THE INVENTION

The present invention relates to novel fluorophenoxyphenoxypropionatesand derivatives thereof which are useful as herbicides. The presentinvention also relates to herbicidal compositions containing these novelcompounds; to methods of using these compounds for the control of weedsin non-crop areas as well as in the presence of valuable crops; and tonovel intermediates used to make these compounds.

Various 4-phenoxy-phenoxy-propionic acids are known as herbicidalagents. U.S. Pat. No. 4,332,961 discloses2-[4-(4-trifluoromethylphenoxy)phenoxy]alkane carboxylic acid andderivatives thereof wherein the "4-trifluoromethylphenoxy group" mayoptionally contain a chloro substituent. U.S. Pat. No. 4,332,960discloses 2-[4-(2-hydrogen orhalogen-4-trifluoromethyl-phenoxy)-phenoxy]propionic acid andderivatives thereof wherein hydrogen is the preferred substituent at the2' position. Both of these patents teach the compounds disclosed in themas possessing herbicidal activity.

U.S. Pat. No. 4,370,489 discloses2-[4-(2-chloro-4-bromo-phenoxy)-phenoxy]propionic acid and derivativesthereof as possessing herbicidal activity.

Heretofore, 2-[4-(2-fluoro-4-substituted-phenoxy)phenoxy]propionic acidsand agriculturally acceptable derivatives thereof have not beendisclosed.

SUMMARY OF THE INVENTION

The present invention is directed to fluorophenoxyphenoxypropionates ofthe formula (I): ##STR1## wherein X represents --Cl, --CF₃, --I, --Br,F, --OCF₃, --CF₂ Cl, --CF₂ H or --OCF₂ CCl₂ H, and

agriculturally acceptable derivatives (salts, amides and esters)thereof.

The compounds of the above Formula I, hereinafter referred to as "activeingredients", have been found to be active as herbicides in the presenceof broadleaf crops and are unexpectedly superior in activity compared tocompounds known in the art. Additionally, compounds of Formula (I),above, wherein X is --Cl and particularly wherein X is --Br, aresurprisingly selective to small grain crops, such as wheat and barley,i.e., substantially non-phytotoxic to small grain crops. Accordingly,the present invention also encompasses herbicidal compositionscontaining one or more active ingredients as well as methods ofcontrolling unwanted vegetation in such crops. Such methods comprise,for example, applying a herbicidally effective amount of one or moreactive ingredients preemergently or postemergently to the locus of theundesired vegetation, and particularly to the locus where a valuablecrop is to germinate and grow.

DETAILED DESCRIPTION OF THE INVENTION

The term "herbicide" is used herein to mean an active ingredient whichcontrols or adversely modifies the growth of plants. By "growthcontrolling" or "herbicidally-effective" amount is meant an amount ofactive ingredient which causes an adversely modifying effect andincludes deviations from natural development, killing, regulation,dessication, retardation, and the like.

The term "plants", when used herein, is meant to include germinant seedsand emerging seedlings as well as established vegetation.

The term "halogen" when used herein is meant to include F, Cl, I and Br.

The term "agriculturally acceptable salts, amides and esters", when usedto describe the active ingredients disclosed herein, is meant toencompass any salt, amide, ester or derivative of said activeingredients (acids) which

(1) does not substantially affect the herbicidal activity of said activeingredients, or

(2) is or can be hydrolyzed and/or oxidized in plants or soil to acarboxyl moiety that is in undissociated and/or dissociated form.

Agriculturally acceptable derivatives of the active ingredients includecompounds of the formula: ##STR2## wherein X represents --Cl, --CF₃,--I, --Br, F, --OCF₃, --CF₂ Cl, --CF₂ H or --OCF₂ CCl₂ H;

R¹ represents C₁ -C₃ alkyl; and

Z represents an organic moiety containing N, O or S atoms, a metalliccation, an ammonium cation, or an organic amine cation and is or can behydrolized and/or oxidized in plants or soil to a carboxyl moiety thatis in undissociated and/or dissociated form.

Z moieties include, but are not limited to

    --(Y).sub.n R.sup.2

wherein

Y represents a saturated or unsaturated alkyl group containing an evennumber of carbon atoms, preferably from 2 to 18 carbon atoms;

n represents 0 or 1;

R² represents moieties corresponding to one of the following formulae:##STR3## wherein M represents a metallic cation, ammonium cation of anorganic amine cation, typically, but not exclusively, containing alkyl(saturated or unsaturated), alicyclic, heterocyclic or aromatic groups,all unsubstituted or substituted with various other groups not limitedto, but including, halo, cyano, nitro and unsubstituted or substitutedthiol, hydroxy, amino or carboxyl groups and, additionally, alicyclic,heterocyclic and aromatic groups substituted with unsubstituted orsubstituted saturated or unsaturated alkyl groups, for example,trifluoromethyl, chloromethyl, cyanomethyl and vinyl; ##STR4## wherein Wrepresents --OR⁶, --SR⁶ or halogen;

A represents O or S;

R³ represents H or R⁶ ;

R⁴ represents H, alkoxy or R⁶ ;

R⁵ represents H, a metallic cation or R⁶ ; and

R⁶ represents an alkyl (saturated or unsaturated), alicyclic,heterocyclic or aromatic group, unsubstituted or substituted withvarious other groups not limited to, but including, halo, cyano, nitroand unsubstituted or substituted thiol, hydroxy, amino or carboxylgroups and, additionally, alicyclic, heterocyclic and aromatic groupssubstituted with unsubstituted or substituted saturated or unsaturatedalkyl groups, for example, trifluoromethyl, chloromethyl, cyanomethyland viny; ##STR5## where R⁷ completes an unsubstituted or substitutedheterocyclic ring system and A represents O or S.

R² is preferably a carboxylic acid group, an alkali or alkaline earthmetal salt thereof, an ammonium or organic amine salt thereof or a loweralkyl ester thereof, wherein "lower alkyl" includes straight, branchedor cyclic saturated or unsaturated alkyl groups containing no more than8 carbon atoms. Preferably, n is 0 and R¹ is methyl.

In Formula (II) above, the aliphatic groups preferably contain 1 to 8carbon atoms, the alkenyl and alkynyl groups preferably contain 2 to 8carbon atoms, the alicyclic groups preferably contain 3 to 8 carbonatoms and the aromatic moiety is preferably phenyl, although other ringsystems, including heterocyclic ring systems, may be employed ifdesired.

In Formula (II) above, X is preferably CF₃, Br or Cl and most preferablyX is Br. The most preferred compounds are those in which X is Br and Zis ##STR6## wherein R" is hydrogen, C₁ -C₈ alkyl, e.g., methyl, ethyl,propyl, isopropyl, isobutyl, n-butyl or n-octyl, or meth-oxypropyl.

The phenoxyphenoxy compounds of Formula (II), also referred to "activeingredients", above are prepared employing procedures analogous to wellknown procedures for preparing known phenoxyphenoxyalkanecarboxylicacids and derivatives thereof as described in the known art. Forexample, some of the compounds of Formula (II) above are prepared byreacting an appropriately substituted 1,2-difluorobenzene with an alkalior alkaline earth metal salt of an appropriate hydroxyphenoxy compoundin a suitable solvent medium, such as dimethylsulfoxide (DMSO),dimethylformamide (DMF), N-methylpyrrolidone, hexamethylphosphoramide,tetrahydrofuran (THF), or acetonitrile. The reaction is advantageouslycarried out at an elevated temperature of from 65° C. to 220° C. Thisreaction can be characterized as follows: ##STR7## wherein X and Z areas hereinbefore defined. This reaction is preferred when preparingcompounds of Formula II wherein X is CF₃ or --NO₂.

Compounds of Formula (II) above wherein X is --Cl or --Br are preferablyprepared by reacting an alkali or alkaline earth metal salt of4-(4-chloro- or bromo-2-fluorophenoxy)phenol with an ##STR8## compound,wherein Z is as defined in Formula (II), in a suitable solvent medium,such as, DMSO, DMF, THF, N-methylpyrrolidone, hexamethylphosphoramide,or acetonitrile. This reaction is advantageously carried out at anelevated temperature of from 40° C. to 220° C. This reaction can becharacterized as follows: ##STR9## wherein X and Z are as hereinbeforedefined and the metallic base is a base, such as, for example Na₂ CO₃ orK₂ CO₃. However, organic bases such as triethylamine can also be used.

4-(4-substituted)-2-fluorophenoxy)phenol and salts thereof are novelintermediate compounds and are within the scope of the presentinvention. These intermediates can be prepared by hydrogenating4-(4-substituted-2-fluorophenoxy)nitrobenzene with hydrogen in thepresence of a Raney nickel catalyst. This reaction can be characterizedas follows: ##STR10## wherein X is as defined hereinbefore.4-(2-Fluoro-4-(substituted)phenoxy)benzeneamine, also a novel compoundand contemplated by the present invention, is reacted with fluoroboricacid (HBF₄), sodium nitrite and water to form the tetrafluoroborate saltof 4-(4-(substituted)-2-fluorophenoxy)benzenediazonium. This reactioncan be characterized as follows: ##STR11## 4-(2-fluoro-4-substitutedphenoxy)benzenediazonium tetrafluoroborate, another novel compound andcontemplated by the present invention, is reacted with (a) aqueoussulfuric acid with heat or (b) an alkali metal trifluoroacetate intrifluoroacetic and water in accordance with the procedures taught in D.E. Horning et al., Can. J. Chem., 51, 2347, (1973), resulting in theformation of 4-(2-fluoro-4-substituted phenoxy)phenol. These reactionscan be characterized as follows: ##STR12##

Preferred compounds of the present invention are the compounds ofFormula (I) above wherein X represents --CF₃, --Br or --Cl, i.e.,4-(2-fluoro-4-(chloro, bromo or trifluoromethyl)phenoxy)phenoxypropionic acid and agriculturally acceptable derivatives thereof. Thesepreferred compounds are prepared by reacting the appropriate startingmaterials employing the procedures set forth above. The4'-trifluoromethyl-2'-fluorophenoxyphenoxy propionates are prepared byreacting 1,2-difluoro-4-trifluoromethylbenzene with a salt of4-hydroxyphenoxypropionic acid or a derivative thereof, i.e., an ester,or amide derivative of the 4-hydroxyphenoxypropionic acid. This reactioncan be characterized as follows: ##STR13## wherein Z' represents --CO₂ H(the acids), --CO₂ M', --CO₂ R⁸, --COSR⁸, --CONR⁹ ₂, --CSNH₂, --CN,--CH₂ OR⁹ or --CH₂ O₂ CR⁹ ;

M' represents Li, Na, K, Mg, Ba or Ca, and corresponds to the cation ofthe metallic base, or N(R¹⁰)₄ ;

R⁸ represents C₁ -C₈ alkyl, C₃ -C₆ cycloalkyl, C₂ -C₈ alkenyl, alkynyl,or alkoxyalkyl;

each R⁹ independently represents H or C₁ -C₄ alkyl; and

R¹⁰ independently represents H, C₁ -C₄ alkyl or C₂ -C₃ hydroxyalkyl.

The 4'-chloro-2'-fluorophenoxyphenoxy propionates are prepared byreacting a 4-(4-chloro-2-fluorophenoxy)phenol with a halopropionate inthe presence of a base and solvent as described above. This reaction canbe characterized as follows: ##STR14## wherein Z' is as defined above.

The 4'-bromo-2'-fluorophenoxyphenoxy propionates are prepared byreacting a 4-(4-bromo-2-fluorophenoxy)phenol with a halopropionate inthe presence of a base and solvent as described above. This reaction canbe characterized as follows: ##STR15## wherein Z' is as defined above.

Alternatively the 2-(4-(4-halo-2-fluorophenoxy)phenoxy)propionates canbe prepared by diazotizing a compound of the following formula:##STR16## where U=O, N and R³ is as previously defined, and decomposingthe diazonium salts using standard techniques to give the desiredhalogenated derivatives as illustrated in some of the followingexamples.

The terms "C₁ -C₄ alkyl" and "C₁ -C₈ alkyl" refer to different sizealkyl groups which may be straight, branched, or cyclic, when the groupcontains at least three carbon atoms, and, contain 1-4 or 1-8 carbonatoms respectively. The terms "C₂ -C₃ hydroxyalkyl" and "C₃ -C₆hydroxyalkyl" refer to different size hydroxyalkyl groups having 2-3 or3-6 carbon atoms, respectively, and the alkyl portion may be straight orbranched, or cyclic when the group contains at least three carbon atoms.

Once prepared, the compounds of the present invention are recoveredemploying standard, well-known extraction and purification techniques,such as, for example, solvent extraction with ether.

The following examples further illustrate the present invention. Noattempt has been made to balance any equations described herein.

EXAMPLE 1 Preparation of2-[4-(2-fluoro-4-trifluoromethylphenoxy)phenoxy]propionic acid methylester ##STR17##

A stirred mixture of potassium fluoride (58 grams (g), 1 mol) andpotassium carbonate (2 g) in sulfolane (300 ml) was subjected to vacuumdistillation until 75 ml of liquid had distilled. This effectivelyremoves any moisture from the system. The distillation head was removedand 4-chloro-3-nitrobenzotrifluoride (95 g, 0.42 mol) was added. Theresulting mixture was heated at 190° C. for two hours, then allowed tocool to approximately 100° C. A 6 inch Vigreaux column was added to thereaction flask, and the product rapidly distilled under vacuum (˜1 mm).The light yellow liquid so obtained was mostly the desired4-fluoro-3-nitrobenzotrifluoride but contained small amounts ofsulfolane (˜4 percent) and starting material. This liquid was dissolvedin pentane (600 ml), washed with water (3×500 ml), then dried (MgSO₄).Removal of the solvent and distillation of the yellow residual liquidgave 59 g (67 percent) of the desired product which had a boiling point(b.p.) of 51° C. at ˜1 mm. The nuclear magnetic resonance (NMR) (CDCl₃)spectra was consistent with the assigned structure. ##STR18##

A mixture of 4-fluoro-3-nitrobenzotrifluoride (59 g, 0.282 mol) andRaney Nickel (RaNi) (Aldrich, 5-spoonula scoops) in ethanol (350 ml) washydrogenated on a Paar apparatus (starting pressure=50 psi) until thetheoretical amount of hydrogen had been consumed (˜7 hours). Thecatalyst was filtered off (celite) and the ethanol was carefullyevaporated on the rotary evaporator (some product is lost in thisprocess). The residue was distilled to give 39 g (77 percent) of thedesired aniline as a nearly colorless liquid which quickly turns yellowon standing. The product had a b.p. of 41° C. at ˜1 mm. The NMR (CDCl₃)spectra was consistent with the assigned structure. ##STR19##

A mechanically stirred solution of 3-amino-4-fluorobenzotrifluoride(17.9 g, 0.1 mol) in 48 percent fluoroboric acid (72 g˜0.4 mol of HBF₄)and water (100 ml) was cooled to ≦5° C. in an ice-salt bath. To thissolution was slowly dropped a solution of sodium nitrite (7.25 g, 0.105mol) in water (10 ml). Soon after the addition began, a solid began toseparate. After about one-quarter of the sodium nitrite solution hadbeen added, the reaction mixture had become very thick. It was necessaryto stir very vigorously with an efficient stirrer in order to completethe reaction. After the addition was complete, stirring at ≦5° C. wascontinued for an hour, then the solid diazonium salt collected byfiltration (medium porosity funnel). The salt was washed with cold 5percent HBF₄ solution (75 ml), then with several portions of cold ether.This material was then dried overnight in a vacuum oven over P₂ O₅ at60° C. to give 22 g (79 percent) of the diazonium tetrafluoroborate(shown above) as an off-white solid. The NMR (d6-acetone) spectra wasconsistent with the assigned structure. ##STR20##

The diazonium salt (22 g) from Step E, which is shown above, was placedin a round-bottom flask (250 ml) equipped with a Dean-Stark trap and acondenser through which ice-water was circulated. The top of thecondenser was connected to a trap containing 10 percent NaOH solution.The flask was immersed in an oil bath heated to 200°-220° C. The saltmelted, turned dark and decomposed slowly, at first, then decomposedmuch more vigorously. The decomposition was accompanied by large amountsof gas and smoke. The desired 3,4-difluoro-benzotrifluoride whichdistilled was collected in the Dean-Stark trap as a dark red liquid (6g). This was taken up in pentane (20 ml) which was then stirred withMgSO₄ and Na₂ CO₃, filtered and distilled to give pure3,4-difluorobenzotrifluoride (3.25 g, 22.5 percent) as a colorlessliquid having a b.p. of 104° C. ##STR21##

A stirred mixture of 3,4-difluorobenzotrifluoride (1.82 g, 0.01 mol),methyl 2-(4-hydroxyphenoxy)propionate (2.72 g, 0.01 mol) and potassiumcarbonate (1.5 g) in DMSO (20 ml) was heated at 100°-110° C. for 90minutes. After cooling, the mixture was poured into water (200 ml), thenextracted with ether (2×100 ml). Pentane (50 ml) was added to the etherextracts, and this was washed with water (200 ml). After drying (MgSO₄)the solvent was evaporated to give the desired phenoxyphenoxypropionate(2.0 g, 55.9 percent) shown above as a pale yellow oil with a refractiveindex (RI) of 1.4998 at 25° C. The NMR (CDCl₃) spectra for ¹ H and ¹⁹ Fwere consistent with the assigned structure.

EXAMPLE 2 Preparation of2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acid methyl ester##STR22##

A stirred solution of 2-fluorophenol (20 g; 0.178 mol) in methylenechloride (200 ml) was cooled to -10° C. in an ice-salt bath.Precondensed chlorine (12.62 g; 0.178 mol) was then slowly bubbled intothe solution at such a rate that the temperature did not rise above -10°C. After all of the chlorine had been added, and the green colordissipated, the reaction was checked by gas chromatography (g.c.). Eventhough no chlorine remained, g.c. showed that besides the twochlorinated products, a fair amount (˜25%) of the starting phenolremained. At this point there was little or no dichlorinated materialpresent. Additional chlorine was bubbled into the reaction mixture untilg.c. showed that all of the starting material had been consumed. At thispoint, the reaction mixture contained 3% of a dichlorinated material aswell as an 8:2 mixture of monochlorinated products. The mixture waspoured into water (300 ml) containing excess sodium bisulfite. Theorganic layer was separated, dried (MgSO₄) and the solvent evaporated togive 25.5 g of a light yellow liquid. Fluorine NMR (CDCl₃) showed thatan 8:2 mixture of monochlorinated products to be present. It waspresumed that the major isomer was the desired 4-chloro-2-fluorophenoland that this would react faster in nucleophillic substitution reactionsthan the more sterically hindered 2-chloro-6-fluorophenol. This mixturewas used directly in the next reaction (Step 2 B). ##STR23##

To a stirred mixture of potassium carbonate (25.04 g; 0.18 mol) in DMSO(200 ml) under argon atmosphere was added an 8:2 mixture (25 g; 0.171mol) (from Step 2A) of 4-chloro-2-fluorophenol (˜20 g; 0.136 mol) and2-chloro-6-fluorophenol (˜5 g; 0.034 mol). To this mixture was added4-fluoronitrobenzene (18.05 g; 0.128 mol) and the resulting mixturestirred at 100° C. for 30 minutes. At the end of this time, g.c. showedthat the mixture contained (peak areas) ˜10% of 2-chloro-6-fluorophenol,˜3% of a dichlorofluorophenol, a trace of 4-chloro-2-fluorophenol, and asingle product peak. This mixture was poured into aqueous base (˜1%NaOH) and the resulting mixture extracted with ether (2×300 ml). Theether extracts were combined, washed with water (an emulsion formedwhich required a little saturated aqueous NaCl to break), dried (MgSO₄)and the solvent removed to given an orange-red oil (34 g). ¹⁹ F NMR(CDCl₃) showed that essentially a single isomer to be present. Thematerial was subjected to Kugelrohr distillation (oven temp.=135°-145°)to give the desired product as a light yellow oil (32 g): RI=1.6038 @25° C. Recrystallization from hexane (freezer) gave the product as awhite solid: m.p.=55°-57° C.

The carbon, hydrogen and nitrogen content was:

    ______________________________________                                                Carbon    Hydrogen  Nitrogen                                          ______________________________________                                        Calculated:                                                                             53.85       2.64      5.23                                          Found:    53.70       2.54      5.16                                          ______________________________________                                         ##STR24##

Raney Nickel, i.e., RaNi (3 scoopulas) was washed with water (2×300 ml)and then ethanol (2×300 ml). To this was added a solution of thephenoxynitrobenzene (29 g; 0.108 g) in ethanol (250 ml). The resultingmixture was hydrogenated in a Paar apparatus (initial H₂ pressure=50psi) until the theoretical amount of hydrogen had been taken up (3-4hours). The mixture was filtered and the solvent evaporated from thefiltrate to give 25 g of a light yellow oil which solidified uponstanding. An analytical sample was prepared by recrystallization fromhexane; m.p.=85.5°-87° C.

The carbon, hydrogen and nitrogen content was:

    ______________________________________                                                Carbon    Hydrogen  Nitrogen                                          ______________________________________                                        Calculated:                                                                             60.64       3.82      5.89                                          Found:    60.49       3.77      5.85                                          ______________________________________                                         ##STR25##

Concentrated hydrochloric acid (35 ml) was added all at once to amechanically stirred suspension of the aniline (16.64 g; 0.07 mol) inwater (70 ml) and the resulting mixture cooled to ≦5° C. in an ice bath.To this stirred mixture was slowly added (dropwise) a solution of sodiumnitrite (5.0 g; 0.072 mol) in water (10 ml). The temperature wasmaintained at ≦8° C. during the addition. By the time the addition wascomplete, the mixture was essentially homogeneous. After stirring at ≦5°C. for an additional 30 minutes, the solution was treated with charcoal,then filtered through celite. The filtrate was again stirredmechanically at ≦5° C. (ice bath) and a solution of sodium fluoroborate(10.98 g; 0.1 mol) in water (35 ml) was added rapidly. A solid separatedimmediately. After stirring for an additional 15 minutes, the solid wasfiltered, washed with a small amount of ice water, then with cold ether(3×150 ml). The solid was air dried for an hour, then completely driedin a vacuum oven over P₂ O₅ at 80° C. for 3 hours. There was thusobtained the desired diazonium tetrafluoroborate (19 g; 84.7%) as anoff-white solid. The NMR (d6 acetone or CF₃ CO₂ H) of this material wasconsistent with the assigned structure and showed a low field,two-proton doublet for the protons ortho to the diazonium salt. Thismaterial was used directly in subsequent reactions. (Step 2E of Example2 and Example 3). ##STR26##

To a stirred solution of concentrated sulfuric acid (8 ml) in water (32ml) which was heated to a gentle boil, was slowly added the abovetetrafluoroborate diazonium salt (from Step 2D) (4 g; 0.0125 mol). Afterthe addition was complete, stirring and heating was contained for 45minutes, then the reaction poured into ice-water (˜300 ml). The mixturewas then extracted with ether (3×100 ml), the combined extracts dried(MgSO₄) and the solvent evaporated to give 1.2 g of a red oil. Thinlayer chromatography (TLC) (silica gel, 7:3 hexane-ethyl acetate) andg.c. showed that this was one main product (phenol) contaminated by aminor product. This red oil was dissolved in DMSO (10 ml), and thenmethyl 2-bromopropionate (0.9 g. 0.0054 mol) and potassium carbonae(0.84 g; 0.006 mol) was added and the resulting mixture stirred under aninert atmosphere overnight. After the addition of water (200 ml), themixture was extracted with ether (2×75 ml). The combined ether extractswere washed with water (75 ml), dried (MgSO₄) and the solvent removed togive 1.3 g of a red oil. NMR (CDCl₃) of this material was consistentwith the desired 2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acidmethyl ester. The oil was chromatographed (130 g silica gel, 7:3hexane-acetone), but this failed to remove the color. The material wastaken up in methanol, treated with charcoal, filtered and evaporated togive a yellow oil: RI=1.5509.

EXAMPLE 3 Preparation of 4-(4-chloro-2-fluorophenoxy)phenol ##STR27##

A solution of potassium trifluoroacetate (0.03 mol) in trifluoroaceticacid (TFA) (60 ml) was prepared by the careful addition of potassiumcarbonate (2.07 g; 0.015 mol) to the trifluoroacetic acid. To thissolution was added, with stirring, the diazonium tetrafluoroborate saltprepared in Example 2, Step 2E, (7.5 g; 0.023 mol) and the resultingmixture stirred and heated at reflux for 48 hours. NMR (CF₃ CO₂ H) ofthe reaction mixture indicated that some diazonium salt remained. Anadditional amount of potassium carbonate (2.07 g; 0.015 mol) was addedand heating continued for 24 hours. Again, NMR indicated that a smallamount of starting material remained. Additional K₂ CO₃ (2.07 g) wasadded and heating continued for 24 hours. NMR now showed that themixture was essentially devoid of starting material. About 30 ml of TFAwas removed by distillation and the resulting mixture poured into water(200 ml). This aqueous mixture was stirred at 40°-45° C. for 3 hours tohydrolyze the trifluoroacetate. After cooling, the mixture was extractedwith ether (3×100 ml), and the ether extracts were treated with charcoaland then filtered through a short pad of silica gel. The filtrate wasevaporated to give a dark viscous residue. This was purified via HPLC(8:2 hexane-ethyl acetate), the second peak being collected. Removal ofthe solvent gave a viscous red oil which was homogeneous by TLC and g.c.NMR (CDCl₃) was consistent with the assigned structure. This materialsolidified upon standing for several days. The methodology employed inthis example is analogous to the methods described in D. E. Horning etal., Can. J. Chem. 51, 2347 (1973).

EXAMPLE 4 Preparation of the R enantiomer of2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acid methyl ester##STR28##

A mixture of 4-(4-chloro-2-fluorophenoxy)phenol (2.23 g; 0.01 mol), themethanesulfonate of S-methyl lactate (18.22 g; 0.1 mol, minimum of 90%optical purity), and potassium carbonate (1.4 g; 0.01 mol) in DMSO (75ml) was stirred at room temperature for 18 hours. After this period, themixture was poured into water (500 ml) then extracted into ether (3×100ml). The ether extracts were dried (MgSO₄), and the solvent evaporated.The residue was purified by preparative HPLC using 8:2hexane-ethylacetate as the eluent. The first peak to elute (after thesolvent front) was collected and the solvent evaporated. This gave 2.3 g(71%) of a light yellow oil whose ¹ H and ¹⁹ F NMR (CDCl₃) wereconsistent with the assigned structure. This material possessed anoptical rotation of +24.68° as measured at 25° C. The refractive indexwas 1.5466. Attempts to measure the optical purity using the opticallyactive NMR shift reagenttris-[3-(trifluoromethylhydroxymethylene)-d-camphorateo] europium (III)were not successful. Based upon the optical purity of the startinglactate the optical purity is estimated to be between 75 and 95%.

EXAMPLE 5 Preparation of 2-[4-(4-bromo-2-fluorophenoxy)phenoxy propionicacid methyl ester ##STR29##

To a stirred solution of 2-fluorophenol (22.4 g, 0.2 mmol) in methylenechloride (250 ml) which was cooled to ˜3° C. in an ice bath, was added,all at once, bromine (31.97 g, 0.2 mol). The resulting solution wasstirred at ice bath temperature for two hours and then at roomtemperature for 1 hour. The mixture was poured into water (600 ml)containing excess sodium bisulfite. The organic phase was separated andthe aqueous phase was washed with additional methylene chloride (200ml). The combined organic extracts were washed with saturated sodiumbicarbonate, dried (MgSO₄) and the solvent evaporated to give thedesired 2-fluoro-4-bromophenol as a colorless oil (34.5 g, 90%). The NMR(CDCl₃) was consistent with the assigned structure. The gc of thismaterial showed that it contained only a trace of the 2,6-isomer. Thismaterial was used directly in the following step without additionalpurification. ##STR30##

To a stirred mixture of 2-fluoro-4-bromophenol (34.0 g, 0.178 mol), and4-fluoronitrobenzene (25.12 g, 0.178 mol) in DMSO (250 ml) was addedpowdered potassium carbonate (27.8 g, 0.2 mol). The resulting mixturewas maintained under an atmosphere of argon and warmed to 100° C. (oilbath temp) for one hour. After cooling, the mixture was poured into anice-cold, 1N NaOH solution (1000 ml) and extracted with ether (3×250ml). The ether extracts were combined, washed with water (300 ml), dried(MgSO₄) and the solvent evaporated to give a yellow oil. This materialwas crystallized from hexane-ether to yield 44.5 g (80%) of the desiredproduct as a light yellow crystalline solid: m.p.=62°-64° C.; NMR(CDCl₃) was consistent with the assigned structure. The carbon, hydrogenand nitrogen content was as follows:

    ______________________________________                                                Carbon    Hydrogen  Nitrogen                                          ______________________________________                                        Calculated:                                                                             46.18       2.26      4.49                                          Found:    46.11       2.22      4.50                                          ______________________________________                                         ##STR31##

Raney nickel (3 spoonulas) was washed with water (3×250 ml) and thenethanol (3×200 ml). To the catalyst covered with a small amount ofethanol, was added a solution of the 4-(4-bromo-2-fluorophenoxy)nitrobenzene from Step III (9.36 g, 0.03 mol) dissolved in warm ethanol (75ml). The solution was degassed with argon, then hydrogenated on a Parrapparatus with an initial hydrogen pressure of 50 psi. When thetheoretical volume of hydrogen had been consumed (˜90 minutes), themixture was degassed, and the catalyst removed via filtration (celite).The solvent was evaporated to give a white solid. Upon recrystallizationof this material from methylcyclohexane, it took on an orange colorationand the recrystallized product was tinted orange. A small amount whichwas recrystallized from hexane did not undergo this apparent slightdecomposition. Regardless of the color, the NMR (CDCl₃) was consistentwith the desired product: m.p.=98°-99.5° C.; Yield=7.7 g (91%). Thecarbon, hydrogen and nitrogen content was as follows:

    ______________________________________                                                Carbon    Hydrogen  Nitrogen                                          ______________________________________                                        Calculated:                                                                             51.08       3.22      4.97                                          Found:    51.10       3.09      4.80                                          ______________________________________                                    

This material was used in the next reaction step. ##STR32##

Concentrated hydrochloric acid (50 ml), (was added all at once to astirred suspension of 4-(4-bromo-2-fluorophenoxy)aniline (30 g, 0.106mol) in water (110 ml). The resulting mixture was cooled to ˜3° C. in anice bath and then a solution of sodium nitrite (8.07 g, 0.117 mol) inwater (15 ml) was slowly added. During the addition, the temperature wasmaintained at ≦8° C. When all of the sodium nitrite had been added, themixture had become a homogeneous solution. After the addition wascomplete, the mixture was stirred at 3° C. for 20 minutes, treated withcharcoal, and filtered through celite. The cold filtrate was poured intoa 1-liter erlynmeyer flask (wide-mouth), equipped with a mechanicalstirrer, and cooled in an ice bath. To this solution, vigorouslystirred, was added a solution of sodium fluoroborate (17.6 g, 0.16 mol)in water (50 ml). A white precipitate separated immediately and themixture was almost too thick to stir. Stirring was continued for 15minutes, then the product filtered (medium porosity funnel), washed withseveral portions of ice water and then with cold ether (3×100 ml). Afterair drying for 30 minutes, the product was dried in a vacuum oven overP₂ O₅ at 80° C. for 3 hours. There was thus obtained 37.5 g (84%) of thedesired diazonium salt, i.e., 4-(4-bromo-2-fluorophenoxy)phenyldiazonium tetrafluoroborate as a white solid. The NMR (CF₃ CO₂ H) wasconsistent with the assigned structure. This material was used directlyin the next reaction step. ##STR33##

Potassium carbonate (34.78 g, 0.25 mol) was carefully and slowly addedto trifluoroacetic acid (200 ml). After the reaction had ceased, thediazonium salt (37 g, 0.097 mol) from Step IV was added, and the stirredsolution heated at reflux for 18 hours. At the end of this period, theNMR of the reaction mixture showed the absence of any starting diazoniumsalt. About half of the trifluoroacetic acid was distilled, then theresidue poured into water (600 ml). This mixture was stirred at 50°-60°C. for 1 hour, cooled, and extracted with ether (3×200 ml). The etherextracts were combined, washed with water, and then with saturatedsodium bicarbonate (3×300 ml). The sodium bicarbonate wash was conductedcarefully because of the generation of foam. The ether phase was thentreated with charcoal and filtered through a short pad of silica gel.The ether was removed to give a yellow-orange oil. The pure phenol wasobtained by prep HPLC (7:3 hexane-ethylacetate) with the second peakbeing collected (1-recycle). Removal of the solvent gave the desiredproduct as an orange oil (19 g, 69%) whose NMR was consistent with theassigned structure. RI=1.6056 @ 25° C. The carbon and hydrogen contentwas as follows:

    ______________________________________                                                     Carbon                                                                              Hydrogen                                                   ______________________________________                                        Calculated:    50.91   2.85                                                   Found:         51.20   2.89                                                   ______________________________________                                         ##STR34##

A mixture of the 4-(4-bromo-2-fluorophenoxy)phenol (5.66 g, 0.02 mol)from Step V, methyl 2-bromoproprionate (3.34 g, 0.02 mol) and potassiumcarbonate (3.06 g, 0.22 mol) in DMSO (30 ml) was stirred, under anatmosphere of nitrogen, at room temperature for 18 hours. The mixturewas poured into water (300 ml), and the resulting mixture extracted withether (2×100 ml). The ether extracts were combined, washed with water(100 ml), dried (MgSO₄), and the solvent evaporated to give the desired2-[4-(4-bromo-2-fluorophenoxy)phenoxy]propionic acid; methyl ester as ayellow oil (6.0 g, 81%); RI=1.5628; NMR (CDCl₃) was consistent with theassigned structure. The carbon and hydrogen content was as follows:

    ______________________________________                                                     Carbon                                                                              Hydrogen                                                   ______________________________________                                        Calculated:    52.05   3.82                                                   Found:         52.12   3.64                                                   ______________________________________                                    

EXAMPLE 6 Preparation of the R enantiomer of2-[4-(4-bromo-2-fluorophenoxy)phenoxy]propionic acid methyl ester##STR35##

A mixture of the 4-(4-bromo-2-fluorophenoxy)phenol (2.83 g, 0.01 mol),the methanesulfonate of S methyl lactate (18.2 g, 0.01 mol), andpotassium carbonate (1.67 g, 0.012 mol) in DMSO (70 ml) was stirred atroom temperature for 40 hours, then poured into water (700 ml). Themixture was extracted with ether (2×200 ml). Pentane (100 ml) was addedto the combined ether extracts and the resulting solution washed withwater (300 ml). The organic phase was dried (MgSO₄) and the solventevaporated to give a light yellow oil (˜7 g). This oil was purified viaprep HPLC (8:2 hexane-acetone) with the first peak being collected.Removal of the solvent gave the desired product enriched in the "R"enantiomer; Optical rotation=+20.34°@25° C. RI=1.5614@25° C.; NMR(CDCl₃) was identical with that obtained in Example 4. No attempt wasmade to determine the optical purity of this material.

EXAMPLE 7 Preparation of 2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propionicacid ##STR36##

A solution of the methyl ester from Example 5 (76 g, 0.206 mol) inethanol (200 ml) was added to a stirred solution of potassium hydroxide(26.4 g, 85% KOH, 0.4 mol) in ethanol (250 ml). The resulting mixturewas stirred for 30 minutes, then the solvent evaporated. The residue wasdissolved in water (200 ml), the resulting solution acidified withconcentrated hydrochloric acid, and then extracted with ether. The etherextracts were dried (MgSO₄) and then the solvent evaporated to give thecrude acid as an off-white solid. Recrystallization frommethylcyclohexane gave 68 g (93%) of the desired acid as a light tansolid. An analytical, sample was prepared by a second recrystallizationfrom methylcyclohexane: m.p.=120°-121° C. Calc. C: 50.72; H: 3.41.Found: C: 50.84; H: 3.46.

EXAMPLE 8 Preparation of 2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propionylchloride ##STR37##

A stirred mixture of the acid from Example 7 (61.8 g, 0.174 mol),benzene (500 ml), thionylchloride (21.77 g, 0.183 mol) anddimethylformamide (DMF, 2 ml) was heated at reflux for one hour. Aftercooling, all volatile material was evaporated to give a quantitativeyield of the crude acid chloride as a bronze colored oil. This materialwas used in subsequent reactions without further purification.

EXAMPLE 9 Preparation of Propionic acid:2-(4-(4-bromo-2-fluorophenoxy)phenoxy), n-butyl ester ##STR38##

To a stirred solution of n-butyl alcohol (0.75 g, 0.01 mol), pyridine(0.8 g, 0.01 mol), and 4-dimethylaminopyridine (DMAP, catalytic amount)in dry ether (30 ml) was slowly dropped a solution of the acid chloride(3.73 g, 0.01 mol) in ether (10 ml). After the addition was complete,the stirred mixture was heated at reflux for one hour, cooled, thenpoured into cold 2N HCl (100 ml). The ether phase was separated, washedwith saturated sodium bicarbonate solution, treated with charcoal, thenfiltered through a pad of silica gel. The filtrate was dried (MgSO₄) andthe solvent evaporated to give the ester as a light yellow oil (3.7 g,90%): Refractive Index (RI)=1.5409 @ 25° C. Calc. C: 55.48; H: 4.90.Found C: 55.74; H: 4.94.

In a similar manner the following esters were prepared:

    ______________________________________                                        Chart I                                                                        ##STR39##                                                                                        Analysis                                                  R             RI or MP    Calc'd   Found                                      ______________________________________                                        OCH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.3                                                       1.5411      C, 53.41 53.50                                                                H,  4.72  4.74                                      OCH.sub.2 (CH.sub.2).sub.6 CH.sub.3                                                         1.5275      C, 59.10 59.26                                                                H,  6.04  5.93                                      OCH.sub.2 CH.sub.2 N(CH.sub.3).sub.2                                                        1.5461      C, 53.53 53.59                                                                H,  4.97  5.01                                                                N,  3.29  3.30                                       ##STR40##    1.5531      C, 56.75 H,  4.76                                                                      56.89  4.91                                OCH.sub.2 CHCH.sub.2                                                                        1.5555      C, 54.70 54.94                                                                H,  4.08  4.12                                      OCH.sub.2 CCH 1.5633      C, 50.40 53.58                                                                H,  3.95  3.62                                       ##STR41##    1.5780      C, 59.34 H,  4.07                                                                      58.83  3.83                                 ##STR42##    1.6031      C, 56.38 H,  3.61                                                                      57.20  3.63                                ______________________________________                                    

EXAMPLE 10 Preparation of2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propionamide ##STR43##

To a cold (approx. 5° C.), stirred mixture of concentrated aqueousammonia (25 ml) and ethyl acetate (25 ml) was slowly dropped a solutionof the acid chloride (3.73 g, 0.01 mol) in ethyl acetate (20 ml). Afterthe addition was complete, the mixture was stirred at room temperaturefor one hour. The organic phase was separated and the aqueous phase wasextracted with a second (50 ml) portion of ethyl acetate. The organicphases were combined, washed with water (75 ml), then with saturatedsodium chloride solution (75 ml), and dried (MgSO₄). Removal of thesolvent gave a quantitive yield of the crude amide as a white solid.Recrystallization from methylcyclohexane gave an analytical sample:m.p.=110°-112° C. Calc: C, 50.87; H, 3.70. Found: C, 51.00; H, 3.75.

EXAMPLE 11 Preparation ofN-Ethyl-N-butyl-2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propionamide##STR44##

To a stirred solution of N-ethyl-N-butylamine (2.12 g, 0.021 mol) and4-dimethylaminopyridine (catalytic amount) in ether (30 ml) was slowlydropped a solution of the acid chloride (3.73 g, 0.01 mol) in ether (10ml). After the addition was complete, the mixture was stirred and heatedat reflux for 30 minutes cooled, then poured into 2N hydrochloric acid(100 ml). The ether phase was separated and the aqueous phase washedwith additional ether (50 ml). The organic phases were combined, washedwith saturated sodium bicarbonate (100 ml), treated with charcoal, thenfiltered through a short pad of silica gel. The filtrate was dried(MgSO₄) and the solvent evaporated to give 3.9 g (89%) of the desiredamide as a light yellow oil: RI=1.5512 @ 25° C. Calc: C, 57.54; H, 5.75.Found: C, 57.55; H, 5.77.

The following derivatives were prepared in a similar manner.

    ______________________________________                                        Chart II                                                                       ##STR45##                                                                                         Analysis                                                 R               RI or MP   Calc'd    Found                                    ______________________________________                                         ##STR46##      1.5944     C, H, N,                                                                            59.47 59.09  4.19  2.93                      NCH.sub.2 CHCH.sub.2                                                                          1.5730     C,    54.83 54.66                                                             H,     4.35  4.21                                                             N.     3.55  3.44                                  NHCH(CH.sub.3).sub.2                                                                          101-104° C.                                                                       C,    54.56 55.28                                                             H,     4.83  4.78                                                             N,     3.54  3.52                                   ##STR47##      137-139° C.                                                                       C, H, N,                                                                            53.03 53.14  3.16  2.76                       ##STR48##      69.5-71° C.                                                                       C, H, N,                                                                            55.19 55.33  3.51  2.93                       ##STR49##      54-55° C.                                                                         C, H, N,                                                                            57.40 58.04  4.34  3.12                       ##STR50##      127-129° C.                                                                       C, H, N,                                                                            54.27 54.12  3.38  2.87                       ##STR51##      1.5954     C, H, N,                                                                            54.68 54.39  3.95  6.08                       ##STR52##      1.5840     C, H, N,                                                                            53.10 52.02  5.11  9.05                      ______________________________________                                    

EXAMPLE 12 Preparation of Propionic Acid:2-(4-(4-bromo-2-fluorophenoxy)phenoxy), 4-nitrophenylhydrazide ##STR53##

To a stirred solution of 4-nitrophenylhydrazine (3.06 g, 0.02 mol) and4-dimethylaminopyridine (catalytic amount) in tetrahydrofuran (THF, 40ml) was slowly dropped a solution of the acid chloride (3.73 g, 01 mol)in THF (10 ml). After the addition was complete, the mixture was stirredfor 30 min at room temperature, then poured into 0.5N hydrochloric acid(150 ml). The product was extracted into ether. The ether phase wastreated with charcoal, filtered through a short pad of silica gel, dried(MgSO₄), then the solvent evaporated to give the desired hydrazide (4.2g, 89%) as an orange solid. Recrystallization from a small volume oftoluene gave an analytical sample: m.p.=177°-180° C. Calc: C, 51.45; H,3.50; N, 8.57. Found: C, 51.63; H, 3.30; N, 8.69.

EXAMPLE 13 Preparation of Methyl2-(4-(2,4-difluorophenoxy)phenoxy)propionate ##STR54##

To a cold (less than 5° C.) stirred solution of the aniline (6.11 g,0.02 mol), concentrated hydrochloric acid (6 ml), and water (50 ml) wasslowly dropped a solution of sodium nitrite (1.52 g, 0.002 mol) in water(10 ml). After the addition was complete, the mixture was stirred for 15minutes then quickly filtered through celite to remove some insolublematerial. The insoluble material was washed with several portions of icewater. To the cold (less than 5° C.), vigorously stirred filtrate andwashings, was added a solution of sodium tetrafluoroborate (4.39 g, 0.04mol) in water (50 ml). The yellow solid which separated was filtered,washed with ether, then dried overnight on a porous plate. The dried,solid diazonium tetrafluoroborate (7.5 g) was placed in a 250 ml roundbottom flask and heated at 190°-200° C. for approximately 5 min. As thesalt melted it decomposed with gas evolution. After cooling, the darkresidue was taken up in ether (150 ml), washed with saturated sodiumbicarbonate, dried (MgSO₄) and purified by preparative HPLC using 8:2hexane/ethyl acetate as the eluent. This first component to elute wascollected, and the solvent evaporated to give the desireddifluorophenoxyphenoxypropionate as a light yellow oil (1.6 g, 28%);RI=1.5276 @ 25° C. Calc: C, 62.33; H, 4.58.Found: C, 62.31; H, 4.43.

EXAMPLE 14 Preparation of2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propionaldehyde ##STR55##

A stirred solution of the ester (3.7 g, 0.01 mol) in toluene (150 mol),under an atmosphere of nitrogen, was cooled to -78° C. using a dryice/acetone cooling bath. To this was slowly dropped a solution ofdiisobutylaluminum hydride (Dibal-H, 11 ml of 1.2M solution, 0.013 mol)in toluene. During the addition the temperature was maintained at lessthan -70° C. After the addition was complete, the mixture was stirred anadditional hour. While maintaining the temperature at less than -70° C.the reaction was quenched by the slow addition of a 75:25:6 ether/aceticacid/water solution (11 ml). The mixture was then warmed to roomtemperature, filtered (filter aid necessary), and the solventevaporated. The oily residue was taken up in ether and passed through ashort column of silica gel. Removal of the solvent gave the desiredaldehyde (3.0 g) as a clear oil: RI=1.5794@25° C. Calc: C, 53.11; H,3.57. Found: C, 52.99; H, 3.62.

The oxime, --CH═NOH, was prepared from the above aldehyde by standardprocedures. It is a glass, having a RI=1.5811. Calc: C, 50.87; H, 3.70;N, 3.96. Found: C, 51.21; H, 3.73; N, 3.89.

Similarly, the ethylene glycol acetal, ##STR56## was prepared from theabove aldehyde by standard procedures. It is a light yellow oil having aRI=1.5678. Calc: 53.28; H, 4.21. Found: C, 53.61; H, 4.08.

EXAMPLE 15 Preparation of 2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propanol##STR57##

In a manner similar to the reduction described above, the ester wasreduced to the corresponding alcohol using slightly more than twoequivalents of Dibal-H. There was thus obtained the desired propanol asa light yellow oil: RI=1.5780 @ 25° C. Calc: C, 52.80; H, 4.14. Found:C, 53.0; H, 4.04.

The benzoate ester, ##STR58## was prepared from the above alcohol bystandard procedures. It is a light yellow oil, RI=1.5798. Calc: C,59.34; H, 4.07. Found: C, 59.35; H, 4.02.

EXAMPLE 16 Preparation ofN-methanesulfonyl-2-(4-bromo-2-fluorophenoxy)phenoxy)propionamide##STR59##

To a stirred solution of methanesulfonamide (1.5 g, 0.016 mol), and4-dimethylaminopyridine (catalytic amount) in pyridine (20 ml) wasslowly added, in a dropwise manner, the neat acid chloride (3.7 g, 0.01mol). The reaction mixture was stirred for 5 days at room temperature,then poured into cold, 2N hydrochloric acid (250 ml). The resultingmixture was extracted with ether (2×100 ml) and the aqueous phasediscarded. The ether phase was then extracted with saturated sodiumbicarbonate (2×50 ml) and the ether phase discarded. The aqueous phasewas acidified to pH less than 4 with concentrated hydrochloric acid. Theaqueous mixture was extracted with ether, the ether phases combined,dried (MgSO₄) and the solvent evaporated to give the desired product asa white solid: m.p. 101°-103° C. Calc: C, 44.46; H, 3.50; N, 3.24.Found: C, 44.45; H, 3.40; N, 3.16.

EXAMPLE 17 Preparation of Propanimidothioic Acid:2-(4-(4-bromo-2-fluorophenoxy)phenoxy)-N-(1-methylethyl)-ethyl)-ethylester. ##STR60##

To a solution of the imide chloride (2.7 g, 0.007 mol) (prepared byheating a solution of the compound in Chart II where R is --NHCH(CH₃)₂with a 10% excess of phosphorous-pentachloride in chloroform for twentyfour hours, then evaporating all volatile material) in drytetrahydrofuran (50 ml) was added solid sodium ethyl mercaptide (1.85 g,0.022 mol) in one portion. The resulting slurry was stirred overnight atroom temperature, then poured into ice water. The organic phase wasseparated, and the aqueous phase was washed with ether. The organicphases were combined, dried (MgSO₄), and the solvent evaporated. Theresidue was purified via preparative HPLC (9:1 hexane/acetone assolvent). The first peak to elute was collected and the solventevaporated to give 1.0 g (32%) of a yellow oil: RI=1.5659 @ 25° C. TheNMR (CDCl₃) of this material showed that it consisted of a 55:45 mixtureof the syn and anti isomers of the desired thioiminoether. Calc: C,54.55; H, 5.26; N, 3.18. Found: C, 54.84; H, 5.09; N, 3.03.

EXAMPLE 18 Preparation of Morpholine:4-(2-(4-(4-bromo-2-fluorobenoxyl)phenoxy)-1-((1-methylethyl)imino)propyl.##STR61##

In a manner similar to that described above, the imide chloride wascondensed with an excess of morpholine in boiling ether. Afterfiltration, and evaporation of the solvent, the residue was partitionedbetween ether and 2N hydrochloride acid. The ether phase was discarded,and the product isolated from the aqueous acid by adjusting the pH to10, and ether extraction. Drying (MgSO₄) and removing the solvent, gavethe desired morpholinoamidine as a viscous yellow oil (1.1 g, 35%):RI=1.5610 @ 25° C. The NMR (CDCl₃) of this material showed it to be amixture of syn and anti isomers. Calc: C, 56.78; H, 5.63; N, 6.02.Found: C, 56.95; H, 5.39; N, 5.89.

EXAMPLE 19 Preparation of2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propanoyl nitrile. ##STR62##

A solution of the amide (1.8 g, 0.0051 mol) and phosphorous oxychloride(POCl₃, 0.86 g, 0.0056 mol) in acetonitrile (20 ml) was stirred andheated at reflux for one hour, then additional POCl₃ (0.5 g) was added.After heating for an additional hour, the cooled reaction mixture waspoured into ice water (300 ml). The aqueous mixture was stirred for afew minutes, then extracted with ether. The ether extracts were washedwith saturated sodium bicarbonate, treated with charcoal, dried (MgSO₄)and the solvent evaporated to give 1.4 g (82%) of the desired nitrile asa light yellow oil: RI=1.5691 @ 25° C. Calc: C, 53.59; H, 3.30; N, 4.17.Found: C, 53.61; H, 3.31; N, 4.21.

Alternatively, various compounds within the scope of the presentinvention may be prepared as illustrated by the following examples andby employing appropriate starting materials.

EXAMPLE 20 Preparation of Methyl2-(4-(2-Fluoro-4-nitrophenoxy)phenoxy)proprionate.

A stirred mixture of 3,4-difluoronitrobenzene (13.5 g, 0.85 mol), methyl2-(4-hydroxyphenoxy)propionate (23.1 g, 0.085 mol), and potassiumcarbonate (12.5 g, 0.09 mol) in DMSO (200 ml) was heated in an oil bath(120° bath temperature) for one hour. After cooling the reaction mixturewas poured into ice water (1000 ml) and the resulting mixture extractedwith ether (3×200 ml). The ether extracts were combined, pentane (200ml) added, and the resulting solution washed with 5% sodium hydroxidesolution (200 ml), then with water. After drying (MgSO₄), the solventwas evaporated to give 28 g (98%) of the desired product as alight-yellow oil which solidified upon standing. Recrystallization fromhexane-ether gave an analytical sample: m.p=67.5°-69° C.; Calc: C,57.31; H, 4.21; N, 4.18. Found: C, 57.00; H, 4.13; N, 4.11.

EXAMPLE 21 Preparation of Methyl 2-(4-(4-Amino-2-fluorophenoxy)phenoxy)propionate.

A solution of the nitro-compound (21.7 g, 0.065 mol) in ethyl acetate(200 ml) containing 5% palladium on charcoal (1.0 g) was subjected tohydrogenation on a Paar shaker (initial pressure=50 psi) until thetheoretical amount of hydrogen had been consumed. The catalyst wasremoved by filtration, and the solvent evaporated to give a quantitativeyield of the desired aniline as a light yellow oil: m.p. (HClsalt)=145°-150° C.; Calc (HCl salt): C, 56.23; H, 5.02; N, 4.10. Found:C, 55.92; H, 4.89; N, 4.04.

EXAMPLE 22 Preparation of Methyl2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propionate.

To a solution of 48% hydrobromic acid (250 ml) and water (350 ml) wasrapidly added the phenoxyaniline (92 g, 0.3 mol). The mixture was warmeduntil the solid, insoluble hydrobromide salt formed. The stirred mixturewas cooled to less than 5° C. in an ice bath, then a solution of sodiumnitrite (22.8 g, 0.33 mol) in water (40 ml) was slowly added. Theaddition was such that the reaction temperature was maintained at lessthan 6° C. After the addition was complete, the mixture was stirred foran additional 15 minutes, then the yellow diazonium solution was added,in a rapid dropwise manner, to a warm, stirred solution of cuprousbromide (47.3 g, 0.33 mol) in 48% hydrobromic acid (100 ml). TheCuBr/HBr solution was maintained at 65°-75° C. by a warm water bath.After all of the diazonium had been added, the dark mixture was stirredan additional 15 minutes, cooled to room temperature, and extracted withether. The ether extracts were combined, washed with saturated sodiumbicarbonate solution, dried (MgSO₄) and the solvent evaporated. Thedark, viscous residue was subjected to bulb-to-bulb distillation to givethe desired product (64 g, 58%).

EXAMPLE 23 Preparation of Ethyl4-(4-(4-Chloro-2-fluorophenoxy)phenoxy)pentanoate.

A stirred mixture of 4-(4-chloro-2-fluorophenoxy)phenol (2.3 g, 0.0103mol), ethyl 4-bromopentanoate (2.01 g, 0.0103 mol), and potassiumcarbonate (1.46 g, 0.105 mol) in DMF (20 ml) was heated in an oil bathat 130° C. for one hour. Additional bromide (0.5 g) and carbonate (0.5g) were added each hour for the next four hours. At the end of thisperiod, gas chromatography indicated that most of the starting phenolhad reacted. After cooling, the reaction mixture was poured into 4N HClsolution (200 ml), and the product extracted into a 1:1 mixture ofether-pentane (2×150 ml). The organic extracts were combined, washedwith 10% NaOH solution (200 ml), dried (MgSO₄), then the solventevaporated. The resulting orange oil was purified via preparative HPLC(9:1 hexane/ethyl acetate) with the second peak being collected. Removalof the solvent gave the desired ester as a light yellow oil: RI=1.5344 @25° C. Calc: C, 62.21; H, 5.50. Found: C, 62.38; H, 5.33.

EXAMPLE 24 Preparation of Methyl4-(4-(Bromo-2-fluorophenoxy)phenoxy)pent-2-enoate.

A stirred mixture of 4-(4-bromo-2-fluorophenoxy)phenol (1.0 g, 0.0035mol), E methyl 4-bromopent-2-enoate (0.71 g, 0.0037 mol) and potassiumcarbonate (0.56 g, 0.004 mol) in acetonitrile (15 ml) was heated atreflux for 90 minutes, then poured into ice water. The resulting mixturewas extracted with ether (2×100 ml). The ether extracts were combined,treated with charcoal, filtered through a short pad of silica gel, dried(MgSO₄), and the solvent evaporated to give the desired product as ayellow oil (1.2 g): RI=1.5660 @ 25° C. Calc: C, 54.70; H, 4.08. Found:C, 54.77; H, 3.79.

EXAMPLE 25 Preparation of Methyl4-(4-(Iodo-2-fluorophenoxy)phenoxy)propionate. ##STR63##

A vigorously stirred mixture of the hydrochloride salt (10.22 g, 0.03mol) in water (125 mol) and concentrated HCl (7.5 ml) was cooled to ≦5°in an ice bath. This resulted in a thick, almost pasty mixture. To thismixture was slowly added a solution of sodium nitrite (2.22 g, 0.032mol) in water (6 ml). As the sodium nitrite was added, the reactionmixture became a homogeneous solution (yellow) containing a small amountof insoluble black polymer. After the addition was complete, thereaction mixture was stirred for an additional 10 min., treated withcharcoal, and the cold solution quickly filtered through celite. Thefiltrate was placed in a 500 ml erlenmeyer flask and again cooled in anice bath. To this stirred solution was carefully added a solution ofpotassium iodide (5.5 g, 0.033 mol) in water (10 ml)--some foamingresulted. The mixture was stirred at room temperature for 1 hr., thenslowly warmed to 60°. The solution containing a dark, viscous gum wascooled to room temperature, then extracted with ether (3 times with 150ml). The ether extracts were combined, washed with sodium bisulfitesolution, dried (MgSO₄) and the solvent evaporated. This mixture waspurified via HPLC (85:15 hexane:acetone) with the first peak beingcollected. Removal of the solvent gave a yellow oil (7.7 g, 61.6percent) whose NMR (CDCl₃, ¹ H and ¹⁹ F) was consistent with theassigned structure; RI=1.5830 at 25° C. Calc: C, 46.17; H, 3.39. Found:C, 46.88; H, 3.35.

EXAMPLE 26 4-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-3-methoxy-2-pentenoicacid, methyl ester

A mixture of 12.0 g (42.4 mmol) 4-(4-bromo-2-fluorophenoxy)phenol, 9.5 g(42.4 mmol) methyl 4-bromo-3-methoxy-2-pentenoate, 6.45 g (46.6 mmol)potassium carbonate and 180 ml acetonitrile was heated at reflux for 16hours. The mixture was poured into water and extracted with ether. Thecombined ether extracts were washed with dilute aqueous NaOH, washedwith water, dried over MgSO₄ and the solvent was removed by rotaryevaporation. The residue was purified by HPLC eluting with 95:5hexane:acetone, to give 10.5 g (58 percent) of the product as a clearcolorless oil. Calc: C, 53.66; H, 4.27. Found: C, 53.28, H, 4.40.Structure was established on the basis of IR and NMR analysis.

EXAMPLE 272-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propanamide-N-methoxy-N-methyl

A mixture of 5.0 g (14.1 mmol)2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propionic acid and 40 ml thionylchloride was heated at reflux for 45 min. The excess SOCl₂ was removedby vacuum distillation.

The acid chloride in 20 ml acetonitrile was added to a mixture of 1.38 g(14.1 mmol) O,N-dimethylhydroxylamine, hydrochloride, 3.57 g (35.2 mmol)triethylamine, and 40 ml acetonitrile, causing an exotherm to 38° C. Themixture was heated at reflux for 31/2 hours.

The mixture was poured into water and extracted with ether. The combinedether layers were washed with saturated NaHCO₃, washed with water, driedover MgSO₄ and the solvent was removed by rotary evaporation. Theresidue was purified by HPLC, eluting with 80:20 hexane:acetone, to give3.65 g (65%) of the product as a white solid: m.p.=72°-75° C. Calc: C,51.28, H, 4.30, N, 3.52. Found: C, 50.90, H, 4.28, N, 3.56. Structurewas established on the basis of IR and NMR analysis.

EXAMPLE 28 4-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-3-oxypentanoate, ethylester

To a solution of 0.8 g (7.8 mmol) diisopropyl amine in 20 ml THF at -78°C., was added 4.9 ml of 1.6M n-butyllithium. To this solution, 0.69 g(7.8 mmol) ethyl acetate in 2 ml THF was added slowly, keeping thetemperature below -74° C., then let stir for 15 min. A solution of 2.7 g(6.8 mmol)2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propanamide-N-methoxy-N-methyl in5 ml THF was added keeping the temperature below -70° C. The solutionwas allowed to warm to 20° C., then poured into 100 ml saturated NH₄ Cland stirred for 30 min. The mixture was extracted with ether. Thecombined ether extracts were dried over MgSO₄ and the solvent wasremoved by rotary evaporation. The residue was purified by HPLC, elutingwith 90:10 hexane:acetone, to give 1.6 g (56%) of the product as ayellow oil. Structure was established on the basis of IR and NMRanalysis. Calc: C, 53.66, H, 4.27. Found: C, 53.91, H, 4.39.

EXAMPLE 294-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-3-methoxy-2-penten-1-ol

To a solution of 4.5 g (10.6 mmol)4-(4-(4-bromo-2-fluorophenoxy)phenoxy)-3-methoxy-2-pentenoic acid,methyl ester in 25 ml toluene at -78° C. was added dropwise over aperiod of 30 min, 16.5 ml of 1.5M DIBAL-H in toluene, keeping thetemperature below -60° C. The mixture was stirred for 21/2 hours at -78°C. To the mixture was added 17 ml of a 75:25:6 ether:acetic acid:watermixture, keeping the temperature below -60° C. The mixture was thenallowed to warm to room temperature and the solid material was filteredoff. The filtrate was washed twice with saturated NaHCO₃ and once withwater, dried over MgSO₄ and the solvent was removed by rotaryevaporation. The residue was purified by HPLC, eluting with 80:20hexane:acetone, to give 3.1 g (74%) of the product as a pale yellow oilwhich was used immediately in the next reaction.

EXAMPLE 30 4-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-3-oxo-1-pentene

To a solution of 30 ml of 35% HClO₄ and 15 ml CH₂ Cl₂ at 0° C. was added3.0 g (7.55 mmol)4-(4-(4-bromo-2-fluorophenoxy)phenoxy)-3-methoxy-2-penten-1-ol in 15 mlCH₂ Cl₂. The mixture was stirred at 0° C. for 45 min, then poured intowater and extracted with ether. The combined ether extracts were washedwith water, dried over MgSO₄ and the solvent was removed by rotaryevaporation. The residue was purified by HPLC, eluting with 95:5hexane:acetone, to give 1.9 g (69%) of the product as a clear, colorlessoil. Structure was established on the basis of IR and NMR analysis.Calc: C, 55.91; H, 3.86. Found: C, 56.84, H, 4.00.

EXAMPLE 313-Acetyl-5-(4-(4-bromo-2-fluorophenoxy)phenoxy)-2,4-hexanedione

A mixture of 1.7 g (17 mmol) of 2,4-pentanedione, 30 ml of benzene and0.26 g (11.3 mmol) of sodium was warmed at reflux for 3 hours. Thereaction mixture was cooled to room temperature and a solution of 10mmol of 2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propanoyl chloride wasadded dropwise. The resulting mixture was warmed at reflux for 2.5hours, stirred at room temperature overnight and poured into water andether. The organic layer was separated, dried over MgSO₄ and evaporatedto dryness. The residue was purified by prep LC, eluting with 4:1hexane:acetone. The product was taken up in ether and extracted with twoportions of 1% aqueous NaOH. The combined aqueous layers were madeacidic with aqueous HCl and extracted with ether. The ether layer wasevaporated to dryness and the residue again purified by prep LC, elutingwith 85:15 hexane:acetone. This gave a yellow oil which was thoroughlydried to leave 0.70 g product. Calc for C₂₀ H₁₈ BrFO₅ : C, 54.93, H,4.15. Found: C, 54.13, H, 4.30.

EXAMPLE 32 4-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-3-hydroxypentanoateethyl ester

A solution of 1.54 ml (11 mmol) of diisopropylamine in 20 ml of etherwas cooled under N₂ to -78° C. and 6.9 ml (11 mmol) of 1.6Mn-butyllithium in hexane was slowly added. After 15 min of -78° C. 0.97g (11 mmol) of ethyl acetate in 3 ml of ether was added dropwise. Theresulting mixture was stirred at -78° C. for 15 min when a solution of3.39 g (10 mmol) of 2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propanaldehydein 5 ml of ether was slowly added. The mixture was allowed to warm toroom temperature, poured into aqueous NH₄ Cl and the aqueous phaseseparated and extracted with ether. The combined organic layers weredried over MgSO₄ and evaporated to dryness and the residue purified byprep LC, eluting with 85:15 hexane:acetone. The resulting colorless oilwas thoroughly dried to leave 2.99 g of product. Structure was confirmedby IR and NMR analysis. Calc. for C₁₇ H₂₀ BrFO₅ : C, 53.41, H, 4.72.Found: C, 53.10, H, 4.66.

EXAMPLE 33 5-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-4-hydroxy-2-hexanone;N,N-dimethylhydrazone

A solution of 2.52 ml (18 mmol) of diisopropylamine and 30 ml of THF wascooled to -78° C. under N₂ and 11.25 ml (18 mmol) of 1.6M n-butyllithiumin hexane was slowly added. A solution of 1.8 g (18 mmol) of acetone;N,N-dimethylhydrazone in 2 ml of THF was added and the resulting mixturestirred at 0° C. for 4 hours. The reaction mixture was cooled to -78°C., a solution of 5.09 g (15 mmol) of2-(4-(4-bromo-2-fluorophenoxy)phenoxy)propanaldehyde in 5 ml of THFadded dropwise and the mixture stirred at -78° C. for 30 min. Afterwarming to room temperature the mixture was poured into water andextracted with two portions of CH₂ Cl₂. The combined organic layers werewashed with water, dried over MgSO₄ and evaporated to dryness. Theresidue was purified by a prep LC, eluting with 4:1 hexane:acetone toleave 3.95 g of product. The structure was confirmed by NMR. Calc forC₂₀ H₂₄ BrFN₂ O₃ : C, 54.67, H, 5.51, N, 6.38. Found: C, 54.48, H, 5.42,N, 5.65.

EXAMPLE 34 5-(4-(4-Bromo-2-fluorophenoxy)phenoxy)-4-hydroxy-2-hexanone

A solution of 2.20 g (5 mmol)5-(4-(4-bromo-2-fluorophenoxy)phenoxy)-4-hydroxy-2-hexanone;N,N-dimethylhydrazone in 15 ml of THF was added to a solution preparedfrom 0.94 g (5.5 mmol) of cupricchloride dihydrate, 60 ml of THF, 15 mlof pH 7.0 phosphate buffer and 25 ml of water. The reaction mixture wasstirred at room temperature for 3 hours, the THF removed on the rotovapand the residue partitioned between CH₂ Cl₂ and aqueous NH₄ Cl/NH₄ OH(pH 8) solution. The organic layer was separated, washed with a freshportion of NH₄ Cl/NH₄ OH solution, dried over MgSO₄ and evaporated todryness. The residue was purified by prep LC, eluting with 77:23hexane:acetone, to give 1.63 g of product as a pale yellow oil. IR andNMR spectra were consistent with desired product. Calc. for C₁₈ H₁₈BrFO₄ : C, 54.42, H, 4.57. Found: C, 54.27, H, 4.64.

The compounds of the present invention, i.e., active ingredients, havebeen found to be suitable for use in methods for the preemergent andpostemergent control of grasses, such as, barnyard grass, crabgrass,yellow foxtail and johnson grass, in the presence of broadleaf crops,such as, cotton, soybeans and sugar beets. Further, it has beensurprisingly found that the compounds of Formula (I) above where X is--Cl or --Br are selective, i.e., exhibit little or no phytotoxiceffects, to small grains such as wheat and barley.

For all such uses, unmodified active ingredients of the presentinvention can be employed. However, the present invention embraces theuse of a herbicidally-effective amount of the active ingredients incomposition form with an inert material known in the art as anagricultural adjuvant or carrier in solid or liquid form. Such adjuvantsor carriers must not be phytotoxic to valuable crops particularly at theconcentration employed in applying the composition in attemptingselective weed control in the presence of crops. If weed control isdesired in the absence of crops, it is generally sufficient to employadjuvants or carriers which do not leave a persistent phytotoxicresidue.

Thus, for example, an active ingredient can be dispersed on afinely-divided solid and employed therein as a dust. Also, the activeingredients, as liquid concentrates or solid compositions comprising oneor more of the active ingredients can be dispersed in water, typicallywith aid of a wetting agent, and the resulting aqueous dispersionemployed as a spray. In other procedures the active ingredients can beemployed as a constituent of organic liquid compositions, oil-in-waterand water-in-oil emulsions or dispersions, with or without the additionof wetting, dispersing, or emulsifying agents.

Suitable adjuvants of the foregoing type are well known to those skilledin the art. The methods of applying the solid or liquid herbicidalformulations similarly are well known to the skilled artisan.

Organic solvents that can be employed include toluene, xylene, kerosene,diesel fuel, fuel oil, and petroleum naphtha, ketones such as acetone,methylethyl ketone and cyclohexanone, chlorinated hydrocarbons such astrichloroethylene, and perchloroethylene, esters such as ethyl acetate,amyl acetate and butyl acetate, ethers, e.g., ethylene glycol monomethylether and diethylene glycol monomethyl ether, alcohols, e.g., methanol,ethanol, isopropanol, amyl alcohol, ethylene glycol, propylene glycol,butylcarbitol acetate and glycerine. Mixtures of water and organicsolvents, either as emulsions or solutions, can be employed.

The active ingredients of the present invention can also be applied asaerosols, e.g., by dispersing them by means of a compressed gas such asone of the fluorocarbons or one of its hydrocarbon successors.

The active ingredients of the present invention can also be applied withsolid adjuvants or carriers such as talc, pyrophyllite, synthetic finesilica, attapulgus clay, kieselguhr, chalk, diatomaceous earth, lime,calcium carbonate, bentonite, Fuller's earth, cotton seed hulls, wheatflour, soybean fluor, pumice, tripoli, wood flour, walnut shell flour,redwood flour and lignin.

As stated, it is frequently desirable to incorporate a surface-activeagent in the compositions of the present invention. Such surface-activeor wetting agents are advantageously employed in both the solid andliquid compositions. The surface-active agent can be anionic, cationicor nonionic in character.

Typical classes of surface-active agents include alkyl sulfonate salts,alkylaryl sulfonate salts, alkylaryl polyether alcohols, fatty acidesters of polyhydric alcohols and the alkylene oxide addition productsof such esters, and addition products of long-chain mercaptans andalkylene oxides. Typical examples of such surface-active agents includethe sodium alkylbenzene sulfonates having 10 to 18 carbon atoms in thealkyl group, alkyl phenol ethylene oxide condensation products, e.g.,p-isooctylphenol condensed with 20 ethylene oxide units, soaps, e.g.,sodium stearate and potassium oleate, sodium salt of propylnaphthalenesulfonic acid, di(2-ethylhexyl)ester of sodium sulfosuccinic acid,sodium lauryl sulfate, sodium decyl sulfonate, sodium salt of thesulfonated monoglyceride of coconut fatty acids, sorbitan sesquioleate,lauryl trimethyl ammonium chloride, octadecyl trimethyl ammoniumchloride, polyethylene glycol lauryl ether, polyethylene glycol estersof fatty acids and rosin acids, e.g., Ethofat® 7 and 13, sodiumN-methyl-N-oleyl taurate, sodium dibutylnaphthalene sulfonate, sodiumlignin sulfonate, polyethylene glycol stearate, sodium dodecyl benzenesulfonate, tertiary dodecyl polyethylene glycol thioether (nonionic218), long-chain ethylene oxide-propylene oxide condensation productse.g., Pluronic® 61 (molecular weight about 1000), polyethylene glycolester of tall oil acids, sodium octophenoxyethoxyethyl sulfate,tris(polyoxyethylene)sorbitan monostearate (Tween® 60), and sodiumdihexylsulfosuccinate.

The concentration of the active ingredients in solid or liquidcompositions generally is from 0.003 to 95 percent by weight or more.Concentrations from 0.05 to 50 percent by weight are often employed. Incompositions to be employed as concentrates, the active ingredient canbe present in a concentration from 5 to 98 weight percent, preferably15-50 weight percent. The active ingredient compositions can alsocontain other compatible additaments, for example, phytotoxicants, plantgrowth regulants, pesticides and the like and can be formulated withsolid particulate fertilizer carriers such as ammonium nitrate, urea andthe like.

Other adjuvants, such as, for example, crop oil and crop oilconcentrates, may also be included in the formulated compositions of theinvention as is known to those skilled in the art.

The present compositions can be applied by the use of power dusters,boom and hand sprayers, spray dusters, by addition to irrigation water,and by other conventional means. The compositions can also be appliedfrom airplanes as a dust or spray since the active ingredients areeffective at very low application rates.

The active ingredients of the present invention have been found topossess desirable herbicidal activity in general against grassy weedssuch as foxtail, blackgrass, johnsongrass, wild oats, barnyard grass andcrabgrass in preemergent operations and also against the same grasses inpostemergent operations. The active ingredients possess desirableherbicidal activity against the grassy weeds, described above, while atthe same time are tolerant or selective to broadleaf crops, such as,cotton, soybeans and sugar beets. The compounds of Formula (I) where Xis --Cl, and particularly where X is --Br, are surprisingly selective tosmall grain crops, such as, wheat and barley.

The exact rate to be applied is dependent not only on a specific activeingredient being applied, but also on a particular action desired (e.g.,general or selective control), the plant species to be modified, and thestage of growth thereof as well as the part of the plant to be contactedwith the toxic active ingredient. Thus, it is to be understood that allof the active ingredients of the present invention and compositionscontaining the same may not be equally effective at similarconcentrations or against the same plant species. In non-selectivepreemergence and foliar treatments, the active ingredients of theinvention are usually applied at an approximate rate of from 0.112 to5.6 kgs/hectare, but higher rates may be appropriate in some cases suchas 22.4 kgs/hectare or more. In preemergent operations for selectiveuses a dosage of 0.112 to 11.2 kgs/hectare or more is generallyapplicable, a rate of 0.112 to 4.48 kgs/hectare being preferred and0.112 to 2.24 kgs/hectare being most preferred. For controlling aninfestation of annuals, a dosage of 0.112 to 0.56 kgs/hectare isgenerally utilized. When the infestation consists largely of perennials,a dosage of from 0.112 to 4.48, preferably 0.56 to 2.24 kgs/hectareshould be employed.

In postemergent operations a dosage of 0.0112 to 22.4 kgs/hectare ormore is generally applicable, although not all compounds are equallyeffective and some weeds are more difficult to control. A dosage rate inthe range of 0.056 to 0.84 kgs/hectare is preferred in selectivepostemergent control of annual grassy weeds, while about 0.112 to 5.6kgs/hectare is preferred and more preferably 0.112 to 2.24 kgs/hectarefor the selective postemergent control of perennial grassy weeds.

EXAMPLE A Postemergent Activity

Representative compositions of the present invention were evaluated forthe postemergence control of species of plants listed in Table A. Inthese evaluations, pots of the plant species listed in Table A, grown toa height of about 10 cms, were used. Aqueous spray compositions,containing various amounts of2-[4-(2-fluoro-4-trifluoromethylphenoxy)-phenoxy]propionic acid methyester, i.e., 125 ppm, 62.5 ppm, 31.25 ppm, 15.6 ppm, 7.8 ppm and 3.9ppm, respectively, were applied to separate pots. The spray compositionswere made by mixing the active ingredient in acetone to 1/2 the finalvolume, i.e., twice the final concentration. An equal amount of waterwas added to the active ingredient/acetone mixture wherein the watercontained 0.1 percent by weight of TWEEN® 200 surfactant. Theapplication to the plants was made to the point of run-off and wascarried out with conventional spraying equipment. Other pots weresprayed with similar compositions containing no toxicant to serve ascontrols. Thereafter, the pots were maintained under conditionsconducive for plant growth. Two weeks after treatment, the pots wereexamined for plant growth and evaluated on a scale of 0 to 100 where 0represents no effect and 100 represents complete kill. The results ofthe examination of the treated pots are set forth below in Table A.

                  TABLE A                                                         ______________________________________                                        % Control at Indicated Dosage (ppm)                                           Plant   125     62.5    31.25 15.6 7.8   3.9  0.0                             ______________________________________                                        Wheat   100     100     100    90   60    0   0                               Barnyard                                                                              100     100     100   100  100   50   0                               Grass                                                                         Crab-   100     100     100   100  100   90   0                               grass                                                                         Yellow  100     100     100   100  100   35   0                               Foxtail                                                                       Johnson 100     100     100   100  100   60   0                               Grass                                                                         Wild Oats                                                                             100     100     100    60   0     0   0                               ______________________________________                                    

At 125 ppm 2-[4-(2-fluoro-4-trifluoromethylphenoxy)phenoxy]propionicacid methyl ester was inactive, i.e., no phytotoxic effect, againstcotton, rape, soybeans, sugar beets, jimson weed, morning glory,pigweed, velvet leaf and cocklebur.

Results of similar postemergent testing of2-(4-(2-fluoro-4-iodophenoxy)phenoxy)propionic acid methyl ester were asfollows:

    ______________________________________                                                   % Control of Indicated Dosage (ppm)                                Plant Species                                                                              125    62.5       31.25                                                                              15.6                                      ______________________________________                                        Wheat         0      0          0   0                                         Barnyard     100    100         85  10                                        Grass                                                                         Crab-        100    100        100  100                                       grass                                                                         Yellow       100    100        100  90                                        Foxtail                                                                       Johnson      100    100        100  90                                        Grass                                                                         Wild Oats     0      0          0    0                                        ______________________________________                                    

EXAMPLE B Postemergent Activity

Substantially the same procedures as those described in Example A wererepeated except that the active ingredients were2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acid; methyl ester andits R-enantiomer and 2-(4-(4-bromo-2-fluorophenoxy)phenoxy propionicacid; methyl ester and its R enantiomer. The results are listed below inTable B.

                  TABLE B                                                         ______________________________________                                        4-Chloro-                                                                     Species    % Control at Indicated Dosage (ppm)                                ______________________________________                                                   500     250     125  62.5 31.25 15.6                               Wheat      40      0       0    0    0     0                                  Barley     50      0       0    0    0     0                                  Wild Oats  100     100     90   95   100   40                                            100    50     25   12.5 6.3  3.1  1.56                             Blackgrass 100    100    99   100  100  50   50                               Cheatgrass 40     10     0    0    0    0    0                                Green Foxtail                                                                            100    100    100  100  100  100  95                               Yellow Foxtail                                                                           100    100    100  100  100  80   50                               ______________________________________                                        4-Chloro- (R-Enantiomer)                                                      Species    % Control at Indicated Dosage (ppm)                                ______________________________________                                                   125      62.5    31.25 15.6  7.8                                   Wheat      60       70      0     0     0                                     Barley     40       0       0     0     0                                     Wild Oats  100      100     100   80    40                                               25     12.5   6.3  3.2   1.6  0.8  0.4                             Blackgrass 100    100    95   90    80   40   0                               Cheatgrass 0      0      0    0     0    0    0                               Green Foxtail                                                                            100    100    100  100   100  80   0                               Yellow Foxtail                                                                           100    100    60   40    0    0    0                               ______________________________________                                        4-Bromo-                                                                      Species  % Control at Indicated Dosage (ppm)                                  ______________________________________                                                 500    250    125  62.5 31.25                                                                              15.6 7.8  3.9                           Wheat    0      0      0    0    0    0    0    0                             Barley   30     10     10   10   0    0    0    0                             Wild Oats                                                                              100    100    95   100  100  100  80   70                                     25     12.5   6.25 3.1  1.5  0.8  0.4  0.2                           Blackgrass                                                                             100    100    99   70   50   30   10   0                             Cheatgrass                                                                             0      0      0    0    0    0    0    0                             Green Fox-                                                                             100    100    100  100  100  90   90   20                            tail                                                                          Yellow Fox-                                                                            100    100    100  80   50   20   0    0                             tail                                                                          ______________________________________                                        4-Bromo- (R-Enantiomer)                                                       Species  % Control at Indicated Dosage (ppm)                                  ______________________________________                                                 250    125    62.5 31.25                                                                              15.6 7.8  3.9  1.9                           Wheat    100    70     0    0    0    0    0    0                             Barley   100    90     95   0    0    0    0    0                             Wild Oats                                                                              100    100    100  90   90   80   80   60                                     12.5   6.3    3.1  1.5  0.8  0.4  0.2  0.1                           Blackgrass                                                                             100    100    90   90   60   50   0    0                             Cheatgrass                                                                             0      0      0    0    0    0    0    0                             Green Fox-                                                                             100    100    100  100  100  100  50   0                             tail                                                                          Yellow Fox-                                                                            100    100    100  60   20   0    0    0                             tail                                                                          ______________________________________                                    

EXAMPLE C Preemergent Activity

In a representative operation,2-[4-(2-fluoro-4-trifluoromethylphenoxy)phenoxy]propionic acid methylester, to be utilized in a series of tests, is dissolved in acetone toone half of the final volume (twice the final concentration) to be usedand the acetone solution in each case is admixed with an equal volume ofwater containing 0.1 percent by weight of Tween-20 surface activematerial (Tween-20 is a trademark of Atlas Chemical Company). Thecomposition, generally in the nature of an emulsion, was employed totreat separate respective seed beds of sandy loam soil of good nutrientcontent wherein each seed bed contained separate groups of good viableseeds, each group being of one of a known plant species. The variousbeds were positioned side by side and exposed to substantially identicalconditions of temperature and light. Each bed was maintained so as toprevent any interaction with the test compound in different seed beds.Each seed bed was treated with the composition as a spray employingconventional spraying equipment to deposit a predetermined amount of thecompound uniformly throughout the surface of the bed. Another seed bedwas treated only with the acetone-Tween-20 water mixture with nochemical added to serve as a control. After treatment, the seed bedswere maintained for two weeks under greenhouse conditions conducive forgood plant growth and watered as necessary. The specific plant species,dosage and the recent preemergent control obtained are set forth inTable C below. Control refers to the reduction in growth of the testspecies in the presence of the test chemical relative to the observedgrowth of the same species in the absence of the test chemical.

                  TABLE C                                                         ______________________________________                                        Preemergence Control of Plant Species (%)                                     Exhibited by 2-[4-(2-fluoro-4-                                                trifluoromethylphenoxy)phenoxy]propionic                                      Acid Methyl Ester                                                                    Plant Species                                                          Dosage           Barn-                                                        in               yard    Crab  Johnson                                                                              Wild Yellow                             Kgs/hectare                                                                            Wheat   Grass   Grass Grass  Oats Foxtail                            ______________________________________                                        0.28     100     100     100   100    100  100                                0.114    100     100     100   100    100  100                                0.07      90      80     100    90     90  100                                0.035     20      70     100    60     20   70                                0.018     0       20      40    20     0    20                                ______________________________________                                         At 0.28 kgs/hectare the compound listed in Table C above was inactive,        i.e., no phytotoxic effect, against the seeds of velvet leaf, rape,           cotton, soybean, pigweed, jimson weed, sugarbeets and yellow nutsedge.   

EXAMPLE D Preemergent Activity of Racemic (R,S)2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic Acid Methyl Ester andits R-enantiomer

Substantially the same procedures described in Example C were repeatedusing as the active ingredients

(1) racemic (R,S) 2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acidmethyl ester and

(2) (R) 2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acid methylester.

The results of the preemergence tests are listed in Table D below.

                                      TABLE D                                     __________________________________________________________________________    Preemergence Control of Plant Species (%)                                     Exhibited by Racemic (R,S,), and Resolved (R)                                 2-[4-(4-Chloro-2-fluorophenoxy)phenoxy]propionic                              Acid Methyl Ester                                                                    Plant Species                                                                      Barn-                                                             Dosage      yard        Johnson   Yellow                                      in     Wheat                                                                              Grass Crabgrass                                                                           Grass                                                                              Wild Oats                                                                          Foxtail                                     Kgs/hectare                                                                          R,S                                                                              R R,S                                                                              R  R,S                                                                              R  R,S                                                                              R R,S                                                                              R R,S                                                                              R                                        __________________________________________________________________________    1.12   0  20                                                                              100                                                                              100                                                                              100                                                                              100                                                                              80 98                                                                              70 80                                                                              95 98                                       0.56   0  10                                                                              100                                                                              100                                                                              100                                                                              100                                                                              60 95                                                                              50 60                                                                              95 95                                       0.28   0   0                                                                               98                                                                               98                                                                              100                                                                              100                                                                               0 80                                                                              20  0                                                                              90 30                                       0.14   0   0                                                                               98                                                                               10                                                                              100                                                                               98                                                                               0  0                                                                               0  0                                                                              10  0                                       0.07   0   0                                                                               40                                                                               0  60                                                                               70                                                                               0  0                                                                               0  0                                                                               0  0                                       __________________________________________________________________________     At 1.12 kgs/hectare the compounds listed in Table D above were inactive,      i.e., no phytotoxic effect, against the seeds of velvet leaf, rape,           cotton, soybean, pigweed, jimson weed, sugarbeets and yellow nutsedge.        EXAMPLE E

Employing the procedures set out above in Example C, the following dataon preemergent activity of various compounds of the present inventionwas obtained.

                                      TABLE E                                     __________________________________________________________________________    Preemergence Control of Plant Species                                          ##STR64##                                                                                           % Control at                                           Compound Tested        Indicated Dosage in kgs/hectare                        X R            Plant Species                                                                         1.12                                                                             .56                                                                              .28 .14                                                                              .07                                       __________________________________________________________________________    Br                                                                               ##STR65##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      0  0  0  50  20  60  0                                                                  0  0  0  0  0  0                            Br                                                                               ##STR66##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      40 100  60  90 100                                                               0  0  0  0  0  70                                                                    0  0  0  0  0  0                            Br                                                                               ##STR67##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      0 100 100  30 100                                                                0 100  30  40  80                                                                0 100  30  0  20                                                                  0  0  0  0  0  0                            Br                                                                              O(CH.sub.2).sub.7 CH.sub.3                                                                 Wheat    90                                                                               0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100  95                                                                               9                                                       Johnsongrass                                                                          100                                                                              100                                                                              100  0  0                                                       Wild Oats                                                                             100                                                                              100                                                                              100  0  0                                                       Yellow Foxtail                                                                        100                                                                               90                                                                               80  0  0                                        Br                                                                              O(CH.sub.2).sub.3 CH.sub.3                                                                 Wheat    30                                                                               30                                                                               0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100  70                                                                               0                                                       Johnsongrass                                                                          100                                                                              100                                                                               65  0  0                                                       Wild Oats                                                                             100                                                                               80                                                                               50  0  0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               95  40                                                                               0                                        Br                                                                              O(CH.sub.2).sub.2 OC.sub.2 H.sub.5                                                         Wheat    20                                                                               0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                               95  90                                                                               0                                                       Johnsongrass                                                                           60                                                                               60                                                                               0   0  0                                                       Wild Oats                                                                             100                                                                              100                                                                               30  30                                                                               0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               80  0  0                                        Br                                                                              OH           Wheat     30                                                                              0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100  95                                                                              50                                                       Johnsongrass                                                                          100                                                                              100                                                                               80  60                                                                               0                                                       Wild Oats                                                                             100                                                                               95                                                                               90 100                                                                               0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               90  0  0                                        Br                                                                              OCH.sub.2CCH Wheat    0  0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100  20                                                                               0                                                       Johnsongrass                                                                          100                                                                              100                                                                               50  20                                                                               0                                                       Wild Oats                                                                              70                                                                               50                                                                               50 NT  0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               95  60                                                                               0                                        Br                                                                              O(CH.sub.2).sub.2 N(CH.sub.3).sub.2                                                        Wheat    0  0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100 100                                                                              70                                                       Johnsongrass                                                                          100                                                                               95                                                                               60  0  0                                                       Wild Oats                                                                              99                                                                               90                                                                               30  30                                                                               0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               0   0  0                                        Br                                                                               ##STR68##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      80 100 100 100 100                                                               0 100 100 100 100                                                                0 100  40  30 100                                                                 0  0 50  0  0  0                            Br                                                                              OCH.sub.2 CCH.sub.2                                                                        Wheat    70                                                                               0  0   0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100 100                                                                              95                                                       Johnsongrass                                                                          100                                                                               90                                                                               80  0  0                                                       Wild Oats                                                                              70                                                                               70                                                                               40  0  0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               90  30                                                                              30                                        Br                                                                              NH.sub.2     Wheat    40                                                                               90                                                                               30  0  0                                                       Barnyardgrass                                                                         100                                                                              100                                                                              100 100                                                                              20                                                       Johnsongrass                                                                          100                                                                               90                                                                               30  0  0                                                       Wild Oats                                                                              95                                                                               50                                                                               50  0  0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               95  90                                                                               0                                        Br                                                                               ##STR69##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      0  0  0  0  0  0  0                                                                     0  0  0  0  0  0                            Br                                                                               ##STR70##   Wheat Barnyardgrass Johnsongrass Wild Oats Yellow                                      0 100 100  90 100                                                                0 100  90  80  90                                                                0 100  50  90  30                                                                 0  0  0   0 80  0                           I OCH.sub.3    Wheat    20                                                                               20                                                                               0   0  0                                                       Barnyardgrass                                                                         100                                                                               97                                                                              100  50                                                                              NT                                                       Johnsongrass                                                                          100                                                                               99                                                                               60  0  0                                                       Wild Oats                                                                              99                                                                               95                                                                               0   0  0                                                       Yellow Foxtail                                                                        100                                                                              100                                                                               20  0  0                                        __________________________________________________________________________     NT = Not Tested                                                          

EXAMPLE F

To further define the selective postemergence herbicidal characteristicsof compounds of the present invention, chemicals were applied toadditional species of grasses as listed in Table F. Chemicals evaluatedwere 2-[4-(4-bromo-2-fluorophenoxy)phenoxy]propionic acid methyl esterand its R isomer. Treatment conditions were similar to those describedin Example A except that chemicals were delivered through a tracksprayer set to deliver the appropriate dosages in 280.6 L/hectare ofwater containing 0.1% Tween-20 surfactant. Results are presented inTable F.

                                      TABLE F                                     __________________________________________________________________________    Racemic Mixture                                                                          Percent Control at Indicated Rate (kgs/hectare)                               0.56                                                                              0.28                                                                             0.14                                                                             0.07                                                                              0.035                                                                            0.018                                                                            0.009                                                                             0.0045                                                                           0.0023                                                                           0.0011                               __________________________________________________________________________    Barley     50  20 10 0   0  0  0   0  0  0                                    Wheat      50  40 10 0   0  0  0   0  0  0                                    Annual Rye 100 100                                                                              100                                                                              100 40 NT 20  0  0  0                                    Wild Oats  100 90 70 40  40 NT 0   0  0  0                                    Goosegrass 100 100                                                                              100                                                                              100 80 NT 20  30 0  0                                    Crabgrass  100 100                                                                              100                                                                              100 100                                                                              NT 50  50 0  0                                    Annual Bluegrass                                                                         0   0  0  0   0  0  0   0  0  0                                    Wild Proso Millet                                                                        100 100                                                                              100                                                                              100 100                                                                              NT 80  70 20 20                                   Green Foxtail                                                                            100 100                                                                              100                                                                              100 100                                                                              NT 90  90 20 0                                    Barnyardgrass                                                                            100 100                                                                              100                                                                              100 100                                                                              NT 100 100                                                                              70 40                                   Johnsongrass                                                                             80  30 20 0   0  NT 0   0  0  0                                    Yellow Foxtail                                                                           100 100                                                                              100                                                                              100 80 NT 40  0  0  0                                    Red Top    100 100                                                                              90 80  50 NT 20  0  0  0                                    Sprangletop                                                                              100 100                                                                              100                                                                              NT  100                                                                              NT 100 95 20 0                                    Fall Panicum                                                                             100 100                                                                              100                                                                              NT  100                                                                              NT 80  50 20 0                                    Giant Foxtail                                                                            100 100                                                                              100                                                                              NT  100                                                                              NT 100 100                                                                              100                                                                              100                                  Tall Fescue                                                                              95  95 90 NT  60 NT 20  20 10 0                                    Canarygrass                                                                              100 100                                                                              100                                                                              100 50 NT 0   0  0  0                                    Broadleaf Signalgrass                                                                    100 100                                                                              100                                                                              100 100                                                                              NT 100 80 90 70                                   Cheatgrass 20  0  0  0   0  0  0   0  0  0                                    Bermudagrass                                                                             100 100                                                                              90 95  90 NT 20  0  0  0                                    Orchardgrass                                                                             90  90 90 80  0  NT 0   0  0  0                                    Downey Brome                                                                             0   0  0  0   0  0  0   0  0  0                                    Blackgrass 100 100                                                                              100                                                                              100 100                                                                              NT 100 50 50 30                                   __________________________________________________________________________    R Resolved Isomer Form                                                                   Percent Control at Indicated Rate (kgs/hectare)                               0.28                                                                             0.14                                                                             0.07                                                                             0.035                                                                            0.018                                                                            0.009                                                                            0.0045                                                                            0.0023                                                                            0.0011                                                                            0.00055                              __________________________________________________________________________    Barley     0  0  0  0  0  0  0   0   0   0                                    Wheat      0  0  0  0  0  0  0   0   0   0                                    Annual Rye 90 90 70 60 30 20 0   0   0   0                                    Wild Oats  95 70 70 40 20 20 0   0   0   0                                    Goosegrass 80 80 70 70 50 70 20  0   0   0                                    Crabgrass  100                                                                              100                                                                              100                                                                              70 90 90 50  0   0   0                                    Annual Bluegrass                                                                         0  0  0  0  0  0  0   0   0   0                                    Wild Proso Millet                                                                        100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              95 100 80  30  30                                   Green Foxtail                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              95 95  90  70  30                                   Barnyardgrass                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 80  90                                   Johnsongrass                                                                             70 40 20 0  0  0  0   0   0   0                                    Yellow Foxtail                                                                           100                                                                              100                                                                              100                                                                              100                                                                              90 50 20  20  0   0                                    Red Top    90 90 90 30 0  0  0   0   0   0                                    Sprangletop                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 20  0                                    Fall Panicum                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              80 80  50  30  20                                   Giant Foxtail                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 100 80                                   Tall Fescue                                                                              90 90 90 80 70 50 20  0   0   0                                    Canarygrass                                                                              100                                                                              100                                                                              100                                                                              100                                                                              0  0  0   0   0   0                                    Broadleaf Signalgrass                                                                    100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              95 90  50  50  50                                   Cheatgrass 0  0  0  0  0  0  0   0   0   0                                    Bermudagrass                                                                             95 90 90 90 60 30 20  0   0   0                                    Orchardgrass                                                                             50 0  0  0  0  0  0   0   0   0                                    Downey Brome                                                                             0  0  0  0  0  0  0   0   0   0                                    Blackgrass 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              80 60  60  60  50                                   __________________________________________________________________________

The compounds of the present invention contain an optically activecenter as shown in Formula (I) (2 position of the propanoic acid) andcan exist in optically active steroisomeric forms such as thedextrorotatory and levorotatory forms of each of the aboveconfigurations. The various mixtures and racemates, i.e., enantiomers,isomers are within the scope of the present invention.

In further embodiments, the compounds of the present invention orcompositions containing the same, can be advantageously employed incombination with one or more additional pesticidal compounds. Suchadditional pesticidal compounds may be insecticides, nematocides,arthropodicides, herbicides, fungicides or bactericides that arecompatible with the compounds of the present invention in the mediumselected for application and not antagonistic to the activity of thepresent compounds. Accordingly, in such embodiments, the pesticidalcompound is employed as a supplemental toxicant for the same or for adifferent pesticidal use, or as an additament. The compounds incombination can generally be present in the ratio of from 1 to 100 partsof the compound of the present invention with from 100 to 1 parts of theadditional compound(s).

In further operations employing the above general procedures and theindicated test compounds the following results were obtained:

    __________________________________________________________________________    Postemergent Control of Plant Species                                          ##STR71##                                                                                          Percent Control at Indicated Dosage (ppm)               R             Plant Species                                                                         250 125 62.5                                                                              31.2                                                                              15.6                                                                             7.8                                  __________________________________________________________________________     ##STR72##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                            NT 100 100 100  50                                                                NT 100 100 100  50                                                                 0 100 100 100  0                                                                   0 80 20 0 0                                                                      0 0 20 0 0                                                                      0 0 0 0 0                             ##STR73##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                            NT 100 100 100  50                                                                NT 100 100 100  0                                                                 NT 100 100 100  0                                                                  0 0 100 100 0                                                                     0 0 70 0 0                                                                      0 0 0 0 0                             ##STR74##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                              0 0 90 98 0                                                                       0 0 95 0 0                                                                        0 0 95 0 0                                                                       0 0 0 0 0                                                                         0 0 0 0 0                                                                       0 0 0 0 0                             ##STR75##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                             0  30 98 100  0                                                                    0 0 98 0 0                                                                       0 0 100 0 0                                                                       0 0 0 0 0                                                                         0 0 0 0 0                                                                       0 0 0 0 0                             ##STR76##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                             0 0 100 100 0                                                                      0 0 98 0 0                                                                        0 0 95 0 0                                                                        0 0 20 0 0                                                                       0 0 0 0 0                                                                       0 0 0 0 0                             ##STR77##    Wheat Barnyardgrass Crabgrass Foxtail Wild                                            NT  0 NT  25  0                                                                     0 0 95 20 0                                                                       0 0 95 0 0                                                                       0 0 0 0 0                                                                         0 0 0 0 0                                                                       0 0 0 0 0                            __________________________________________________________________________

What is claimed is:
 1. The compound which is2-[4-(4-bromo-2-fluorophenoxy)phenoxy]propionyl nitrile.
 2. The compoundof claim 1 which is the R-enantiomer.
 3. Ethyl4-[4-(4-chloro-2-fluorophenoxy)phenoxy]pentanoate.
 4. Methyl4-[4-(bromo-2-fluorophenoxy)phenoxy]pent-2-enoate.
 5. Morpholine:4-(2-(4-bromo-2-fluorophenoxy)phenoxy)-1-((1-methylethyl)imino)propyl.6. Propanimidothioic acid:2-(4-(4-bromo-2-fluorophenoxy)phenoxy)-N-((1-methylethyl)ethyl)ethylester.7. N-methanesulfonyl-(2-(4-bromo-2-fluorophenoxy)phenoxy)propionamide.8. 2-(4-(4-Bromo-2-fluorophenoxy)phenoxy)propanol.